What do you get with Print?

Instant access to your digital copy whilst your Print order is Shipped

Paperback book shipped to your preferred address

Redeem a companion digital copy on all Print orders

Access this title in our online reader with advanced features

DRM FREE - Read whenever, wherever and however you want

AI Assistant (beta) to help accelerate your learning

View table of contents

Preview Book

The Ultimate Linux Shell Scripting Guide

Getting Started with the Shell

Before we can talk about shell scripting, we need to know what a shell is and what kinds of shells are available for Linux, Unix, and Unix-like operating systems. We’ll also talk about other important topics that will help get you started in the wide, wonderful world of shell scripting.

Topics in this chapter include:

Understanding shells
Finding help with shell commands
Using a text editor
Understanding compiled versus interpreted programming
Understanding root and sudo privileges

If you’re ready, let’s get started on this important journey. And, always remember to have some fun along the way.

Understanding Shells

So, you’re scratching your head and saying, “What is a shell, and why should I care?” Well, a shell is a program that acts as an intermediary between the user and the operating system kernel. A user types commands into the shell, which passes them into the kernel for processing. The output is then presented to the user via the computer terminal, which can also referred to as the screen. The most common shell on Linux systems is bash, but the Z shell (zsh) has been gaining popularity in recent years. (I’ll explain why in Chapter 22, Using the Z Shell.) You’ll find bash as the default shell on most Linux distros and certain Unix-like distros such as OpenIndiana, and zsh as the default on Kali Linux.

If you are brand new to the wild, wonderful world of Linux and its Unix or Unix-like cousins, you might be wondering what a distro is. Well, unlike Windows and macOS, which are proprietary and controlled by a single company, Linux and its cousins are primarily open source software, which means that anyone can take the source code and create their own implementations, or distributions. Red Hat Enterprise Linux, Fedora, and Ubuntu are examples of Linux distributions, and OpenIndiana and FreeBSD are examples of Unix-like distributions. But, we hard-core geeks rarely utter the word distribution, and instead just say distro, for short.

Also, the reason that I differentiate between Unix and Unix-like distros has to do with legal reasons that date back to the 1980s. This involves a rather complicated mess that I would rather not go into here. Suffice it to say that the creators of distros such as FreeBSD are not allowed to refer to their creations as Unix, even though they are mostly functionally equivalent. But, they can say that their creations are Unix-like.

The newest versions of macOS also have zsh set as the default shell. Fortunately, much of what you’ll learn about bash also works on zsh. The main difference is that zsh has a few cool features that bash doesn’t have. (Again, I’ll explain all about that in Chapter 22.) PowerShell, which originally was only available for Microsoft Windows operating systems, has also been available for Linux and macOS since 2016. PowerShell is a whole different animal, but you might find it quite useful, as you should see when we get to Chapter 23, Using PowerShell on Linux.

It’s common to hear people refer to bash as the bash shell. But, bash is short for Bourne Again Shell. So, when you say bash shell, you’re really saying Bourne Again Shell Shell, which is a bit awkward. This is the same as when people talk about going to the ATM machine to withdraw some money. What they’re really saying is that they’re going to the Automatic Teller Machine Machine, which is also awkward.

And, don’t even get me started on the people who talk about hot water heaters. I mean, if the water is already hot, why heat it?

On the other hand, if you find that you still need to say bash shell so that people will know what you’re talking about, I’ll understand and won’t condemn you for it. In fact, you might even see me do that on occasion.

The coolest thing about modern operating system shells is that they’re much more than just an interface tool. They’re also full-blown programming environments with many of the same programming constructs as more complex programming languages, such as Pascal, C, or Java. Systems administrators can make their jobs much easier by using shell scripts to automate complex, repetitive tasks.

When you log into a text-mode Linux or Unix server, you’ll be presented with a black screen and some text, which looks like this:

Figure 1.1: Plain bash on a text-mode Debian Linux machine

This is the unadorned, plain-jane shell. Machines with desktop environments installed will interface with the shell via a terminal emulator, which will look something like this:

Figure 1.2: A terminal emulator that interfaces with bash on an OpenIndiana machine

The name of the terminal emulator will differ from one desktop environment to the next, but all do the same job. The advantage of using a terminal emulator is that you’ll have the luxury of using scroll bars, customizing the display, and using copy-and-paste for the command-line.

In any case, you can see which shell you’re using by typing:

donnie@fedora:~$ echo $SHELL
/bin/bash
donnie@fedora:~$

In this case, you see that you’re using bash.

Download Code

Key benefits

Develop portable scripts using Bash, Zsh, and PowerShell that work seamlessly across Linux, macOS, and Unix systems

Progress seamlessly through chapters with clear concepts, practical examples, and hands-on labs for skill development

Build real-world Linux administration scripts, enhancing your troubleshooting and management skills

Description

Dive into the world of Linux shell scripting with this hands-on guide. If you’re comfortable using the command line on Unix or Linux but haven’t fully explored Bash, this book is for you. It’s designed for programmers familiar with languages like Python, JavaScript, or PHP who want to make the most of shell scripting. This isn’t just another theory-heavy book—you’ll learn by doing. Each chapter builds on the last, taking you from shell basics to writing practical scripts that solve real-world problems. With nearly a hundred interactive labs, you’ll gain hands-on experience in automation, system administration, and troubleshooting. While Bash is the primary focus, you'll also get a look at Z Shell and PowerShell, expanding your skills and adaptability. From mastering command redirection and pipelines to writing scripts that work across different Unix-like systems, this book equips you for real-world Linux challenges. By the end, you'll be equipped to write efficient shell scripts that streamline your workflow and improve system automation.

Who is this book for?

This book is for programmers who use the command line on Unix and Linux servers already, but don't write primarily in Bash. This book is ideal for programmers who've been using a scripting language such as Python, JavaScript or PHP, and would like to understand and use Bash more effectively. It’s also great for beginning programmers, who want to learn programming concepts.

What you will learn

Grasp the concept of shells and explore their diverse types for varied system interactions

Master redirection, pipes, and compound commands for efficient shell operations

Leverage text stream filters within scripts for dynamic data manipulation

Harness functions and build libraries to create modular and reusable shell scripts

Explore the basic programming constructs that apply to all programming languages

Engineer portable shell scripts, ensuring compatibility across diverse platforms beyond Linux

What do you get with Print?

Instant access to your digital copy whilst your Print order is Shipped

Paperback book shipped to your preferred address

Redeem a companion digital copy on all Print orders

Access this title in our online reader with advanced features

DRM FREE - Read whenever, wherever and however you want

AI Assistant (beta) to help accelerate your learning

FAQs

What is the digital copy I get with my Print order?

When you buy any Print edition of our Books, you can redeem (for free) the eBook edition of the Print Book you’ve purchased. This gives you instant access to your book when you make an order via PDF, EPUB or our online Reader experience.

What is the delivery time and cost of print book?

Shipping Details

USA:

Economy: Delivery to most addresses in the US within 10-15 business days

Premium: Trackable Delivery to most addresses in the US within 3-8 business days

UK:

Economy: Delivery to most addresses in the U.K. within 7-9 business days.
Shipments are not trackable

Premium: Trackable delivery to most addresses in the U.K. within 3-4 business days!
Add one extra business day for deliveries to Northern Ireland and Scottish Highlands and islands

EU:

Premium: Trackable delivery to most EU destinations within 4-9 business days.

Australia:

Economy: Can deliver to P. O. Boxes and private residences.
Trackable service with delivery to addresses in Australia only.
Delivery time ranges from 7-9 business days for VIC and 8-10 business days for Interstate metro
Delivery time is up to 15 business days for remote areas of WA, NT & QLD.

Premium: Delivery to addresses in Australia only
Trackable delivery to most P. O. Boxes and private residences in Australia within 4-5 days based on the distance to a destination following dispatch.

India:

Premium: Delivery to most Indian addresses within 5-6 business days

Rest of the World:

Premium: Countries in the American continent: Trackable delivery to most countries within 4-7 business days

Asia:

Premium: Delivery to most Asian addresses within 5-9 business days

Disclaimer:
All orders received before 5 PM U.K time would start printing from the next business day. So the estimated delivery times start from the next day as well. Orders received after 5 PM U.K time (in our internal systems) on a business day or anytime on the weekend will begin printing the second to next business day. For example, an order placed at 11 AM today will begin printing tomorrow, whereas an order placed at 9 PM tonight will begin printing the day after tomorrow.

Unfortunately, due to several restrictions, we are unable to ship to the following countries:

Afghanistan
American Samoa
Belarus
Brunei Darussalam
Central African Republic
The Democratic Republic of Congo
Eritrea
Guinea-bissau
Iran
Lebanon
Libiya Arab Jamahriya
Somalia
Sudan
Russian Federation
Syrian Arab Republic
Ukraine
Venezuela

What is custom duty/charge?

Customs duty are charges levied on goods when they cross international borders. It is a tax that is imposed on imported goods. These duties are charged by special authorities and bodies created by local governments and are meant to protect local industries, economies, and businesses.

Do I have to pay customs charges for the print book order?

The orders shipped to the countries that are listed under EU27 will not bear custom charges. They are paid by Packt as part of the order.

List of EU27 countries: www.gov.uk/eu-eea:

A custom duty or localized taxes may be applicable on the shipment and would be charged by the recipient country outside of the EU27 which should be paid by the customer and these duties are not included in the shipping charges been charged on the order.

How do I know my custom duty charges?

The amount of duty payable varies greatly depending on the imported goods, the country of origin and several other factors like the total invoice amount or dimensions like weight, and other such criteria applicable in your country.

For example:

If you live in Mexico, and the declared value of your ordered items is over $ 50, for you to receive a package, you will have to pay additional import tax of 19% which will be $ 9.50 to the courier service.
Whereas if you live in Turkey, and the declared value of your ordered items is over € 22, for you to receive a package, you will have to pay additional import tax of 18% which will be € 3.96 to the courier service.

How can I cancel my order?

Cancellation Policy for Published Printed Books:

You can cancel any order within 1 hour of placing the order. Simply contact customercare@packt.com with your order details or payment transaction id. If your order has already started the shipment process, we will do our best to stop it. However, if it is already on the way to you then when you receive it, you can contact us at customercare@packt.com using the returns and refund process.

Please understand that Packt Publishing cannot provide refunds or cancel any order except for the cases described in our Return Policy (i.e. Packt Publishing agrees to replace your printed book because it arrives damaged or material defect in book), Packt Publishing will not accept returns.

What is your returns and refunds policy?

Return Policy:

We want you to be happy with your purchase from Packtpub.com. We will not hassle you with returning print books to us. If the print book you receive from us is incorrect, damaged, doesn't work or is unacceptably late, please contact Customer Relations Team on customercare@packt.com with the order number and issue details as explained below:

If you ordered (eBook, Video or Print Book) incorrectly or accidentally, please contact Customer Relations Team on customercare@packt.com within one hour of placing the order and we will replace/refund you the item cost.
Sadly, if your eBook or Video file is faulty or a fault occurs during the eBook or Video being made available to you, i.e. during download then you should contact Customer Relations Team within 14 days of purchase on customercare@packt.com who will be able to resolve this issue for you.
You will have a choice of replacement or refund of the problem items.(damaged, defective or incorrect)
Once Customer Care Team confirms that you will be refunded, you should receive the refund within 10 to 12 working days.
If you are only requesting a refund of one book from a multiple order, then we will refund you the appropriate single item.
Where the items were shipped under a free shipping offer, there will be no shipping costs to refund.

On the off chance your printed book arrives damaged, with book material defect, contact our Customer Relation Team on customercare@packt.com within 14 days of receipt of the book with appropriate evidence of damage and we will work with you to secure a replacement copy, if necessary. Please note that each printed book you order from us is individually made by Packt's professional book-printing partner which is on a print-on-demand basis.

What tax is charged?

Currently, no tax is charged on the purchase of any print book (subject to change based on the laws and regulations). A localized VAT fee is charged only to our European and UK customers on eBooks, Video and subscriptions that they buy. GST is charged to Indian customers for eBooks and video purchases.

What payment methods can I use?

You can pay with the following card types:

Visa Debit
Visa Credit
MasterCard
PayPal

What is the delivery time and cost of print books?

Shipping Details

USA:

Economy: Delivery to most addresses in the US within 10-15 business days

Premium: Trackable Delivery to most addresses in the US within 3-8 business days

UK:

Economy: Delivery to most addresses in the U.K. within 7-9 business days.
Shipments are not trackable

Premium: Trackable delivery to most addresses in the U.K. within 3-4 business days!
Add one extra business day for deliveries to Northern Ireland and Scottish Highlands and islands

EU:

Premium: Trackable delivery to most EU destinations within 4-9 business days.

Australia:

India:

Premium: Delivery to most Indian addresses within 5-6 business days

Rest of the World:

Premium: Countries in the American continent: Trackable delivery to most countries within 4-7 business days

Asia:

Premium: Delivery to most Asian addresses within 5-9 business days

Unfortunately, due to several restrictions, we are unable to ship to the following countries:

Afghanistan
American Samoa
Belarus
Brunei Darussalam
Central African Republic
The Democratic Republic of Congo
Eritrea
Guinea-bissau
Iran
Lebanon
Libiya Arab Jamahriya
Somalia
Sudan
Russian Federation
Syrian Arab Republic
Ukraine
Venezuela

A. Zubarev Oct 24, 2024

This book is probably one of, if not the most, comprehensive of all on the capabilities of scripting on Linux.It covers all the common scripting shells, even PowerShell (who knew it would be possible to run Microsoft's shell on Linux?!), methods of securing scripts, text manipulation, advanced scripting techniques including automation, shell configuration, error handling, piping and much more.I especially liked the chapters on image manipulations and creating user interfaces.Be aware that this book assumes you are scripting for an on-prem resident machine and it is probably the only shortcoming I can mention.

Amazon Verified review

N/A Jan 30, 2025

Feefo Verified review

Byron Gorman Nov 15, 2024

The Ultimate Linux Shell Scripting, is an extremely fascinating read. So let’s get right to the contents of the book. First the book sets you up for success by providing you with examples of code, that you will use with the hands on labs that personally I found to be intriguing. This allows the reader to jump into the thick of Linux from the start. The labs are presented so the reader can have a better understanding of the processes and code automation, the rich contents covers everything from learning the shell and shell emulators to using Powershell on Linux and macOS. This allows the reader the opportunity to explore Linux using several different flavors. Starting with the shell you will learn simple commands that will show you the difference between the regular user and the root user. Then we step into commands and how to leverage them in your favor. By automating some Linux scripts you will be able to customize your environment and do global configurations.The book also allows you to create basic shell scripts, and filter them and the steps you through advanced scripts. This read is full of examples and illustrations that show how the script commands are used and the end result you should be seeing.At the end of each chapter there are review questions to make certain that you have maintained the correct information.If you are new to Linux, attempting to get your certification or are a seasoned Linux user this is one book to add to you’re personal Linux war chest. I added it to mine! Read more

Emiru Mar 01, 2025

I am giving 4 stars because i am still on chapter 2 but I love the writer's approach to the subject matter. I have been using Linux now for 10+ years and the teaching style has knowledge for every level.

Subscriber review

The Ultimate Linux Shell Scripting Guide: Automate, Optimize, and Empower tasks with Linux Shell Scripting

What do you get with Print?

The Ultimate Linux Shell Scripting Guide

Getting Started with the Shell

Understanding Shells

Page 1 of 11

Key benefits

Description

Who is this book for?

What you will learn

Product Details

What do you get with Print?

Product Details

Table of Contents

Recommendations for you

Customer reviews

About the author

FAQs

The Ultimate Linux Shell Scripting Guide: Automate, Optimize, and Empower tasks with Linux Shell Scripting

What do you get with Print?

Contact Details

Shipping Address

Billing Address

Key benefits

Description

Who is this book for?

What you will learn

Product Details

What do you get with Print?

Contact Details

Shipping Address

Billing Address

Product Details

Packt Subscriptions

Table of Contents

Recommendations for you

Customer reviews

About the author

FAQs